treewide: rework code to get rid of fixed IPv6 address arrays
[project/odhcpd.git] / src / odhcpd.c
index 3fb3009..ee628a5 100644 (file)
 #include <unistd.h>
 #include <signal.h>
 #include <stdbool.h>
+#include <syslog.h>
+#include <alloca.h>
 
 #include <arpa/inet.h>
 #include <net/if.h>
 #include <netinet/ip6.h>
 #include <netpacket/packet.h>
+#include <linux/netlink.h>
+#include <linux/if_addr.h>
+#include <linux/neighbour.h>
 #include <linux/rtnetlink.h>
 
 #include <sys/socket.h>
 #include <sys/wait.h>
 #include <sys/syscall.h>
 
+#include <netlink/msg.h>
+#include <netlink/socket.h>
+#include <netlink/attr.h>
 #include <libubox/uloop.h>
 #include "odhcpd.h"
 
 
 
 static int ioctl_sock;
-static int rtnl_socket = -1;
-static int rtnl_seq = 0;
+static struct nl_sock *rtnl_socket = NULL;
 static int urandom_fd = -1;
 
-
 static void sighandler(_unused int signal)
 {
        uloop_end();
 }
 
+static void print_usage(const char *app)
+{
+       printf(
+       "== %s Usage ==\n\n"
+       "  -h, --help   Print this help\n"
+       "  -l level     Specify log level 0..7 (default %d)\n",
+               app, config.log_level
+       );
+}
 
-int main()
+int main(int argc, char **argv)
 {
        openlog("odhcpd", LOG_PERROR | LOG_PID, LOG_DAEMON);
-       setlogmask(LOG_UPTO(LOG_WARNING));
+       int opt;
+
+       while ((opt = getopt(argc, argv, "hl:")) != -1) {
+               switch (opt) {
+               case 'h':
+                       print_usage(argv[0]);
+                       return 0;
+               case 'l':
+                       config.log_level = (atoi(optarg) & LOG_PRIMASK);
+                       fprintf(stderr, "Log level set to %d\n", config.log_level);
+                       break;
+               }
+       }
+       setlogmask(LOG_UPTO(config.log_level));
        uloop_init();
 
        if (getuid() != 0) {
@@ -68,8 +96,8 @@ int main()
 
        ioctl_sock = socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, 0);
 
-       if ((rtnl_socket = odhcpd_open_rtnl()) < 0) {
-               syslog(LOG_ERR, "Unable to open socket: %s", strerror(errno));
+       if (!(rtnl_socket = odhcpd_create_nl_socket(NETLINK_ROUTE))) {
+               syslog(LOG_ERR, "Unable to open nl socket: %s", strerror(errno));
                return 2;
        }
 
@@ -96,19 +124,24 @@ int main()
        return 0;
 }
 
-int odhcpd_open_rtnl(void)
+struct nl_sock *odhcpd_create_nl_socket(int protocol)
 {
-       int sock = socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, NETLINK_ROUTE);
+       struct nl_sock *nl_sock;
 
-       // Connect to the kernel netlink interface
-       struct sockaddr_nl nl = {.nl_family = AF_NETLINK};
-       if (connect(sock, (struct sockaddr*)&nl, sizeof(nl))) {
-               syslog(LOG_ERR, "Failed to connect to kernel rtnetlink: %s",
-                               strerror(errno));
-               return -1;
-       }
+       nl_sock = nl_socket_alloc();
+       if (!nl_sock)
+               goto err;
+
+       if (nl_connect(nl_sock, protocol) < 0)
+               goto err;
 
-       return sock;
+       return nl_sock;
+
+err:
+       if (nl_sock)
+               nl_socket_free(nl_sock);
+
+       return NULL;
 }
 
 
@@ -174,12 +207,6 @@ ssize_t odhcpd_send(int socket, struct sockaddr_in6 *dest,
                        || IN6_IS_ADDR_MC_LINKLOCAL(&dest->sin6_addr))
                dest->sin6_scope_id = iface->ifindex;
 
-       // IPV6_PKTINFO doesn't really work for IPv6-raw sockets (bug?)
-       if (dest->sin6_port == 0) {
-               msg.msg_control = NULL;
-               msg.msg_controllen = 0;
-       }
-
        char ipbuf[INET6_ADDRSTRLEN];
        inet_ntop(AF_INET6, &dest->sin6_addr, ipbuf, sizeof(ipbuf));
 
@@ -193,146 +220,257 @@ ssize_t odhcpd_send(int socket, struct sockaddr_in6 *dest,
        return sent;
 }
 
+struct addr_info {
+       int ifindex;
+       struct odhcpd_ipaddr **addrs;
+       int pending;
+       ssize_t ret;
+};
 
-int odhcpd_iterate_interface_neighbors(const struct interface *iface,
-               void(*cb_neigh)(const struct in6_addr *addr,
-                               const struct interface *iface, void *data), void *data)
+static int cb_valid_handler(struct nl_msg *msg, void *arg)
 {
-       struct {
-               struct nlmsghdr nhm;
-               struct ndmsg ndm;
-       } req = {{sizeof(req), RTM_GETNEIGH, NLM_F_REQUEST | NLM_F_DUMP,
-                       ++rtnl_seq, 0}, {AF_INET6, 0, 0, iface->ifindex, 0, 0, 0}};
+       struct addr_info *ctxt = (struct addr_info *)arg;
+       struct odhcpd_ipaddr *addrs = *(ctxt->addrs);
+       struct nlmsghdr *hdr = nlmsg_hdr(msg);
+       struct ifaddrmsg *ifa;
+       struct nlattr *nla[__IFA_MAX];
 
-       if (send(rtnl_socket, &req, sizeof(req), 0) < (ssize_t)sizeof(req))
-               return -1;
+       if (hdr->nlmsg_type != RTM_NEWADDR)
+               return NL_SKIP;
 
-       uint8_t buf[8192];
-       ssize_t len = 0;
-
-       for (struct nlmsghdr *nhm = NULL; ; nhm = NLMSG_NEXT(nhm, len)) {
-               while (len < 0 || !NLMSG_OK(nhm, (size_t)len)) {
-                       len = recv(rtnl_socket, buf, sizeof(buf), 0);
-                       nhm = (struct nlmsghdr*)buf;
-                       if (len < 0 || !NLMSG_OK(nhm, (size_t)len)) {
-                               if (errno == EINTR)
-                                       continue;
-                               else
-                                       return -1;
-                       }
-               }
+       ifa = NLMSG_DATA(hdr);
+       if (ifa->ifa_scope != RT_SCOPE_UNIVERSE ||
+                       (ctxt->ifindex && ifa->ifa_index != (unsigned)ctxt->ifindex))
+               return NL_SKIP;
 
-               if (nhm->nlmsg_type != RTM_NEWNEIGH)
-                       break;
+       nlmsg_parse(hdr, sizeof(*ifa), nla, __IFA_MAX - 1, NULL);
+       if (!nla[IFA_ADDRESS])
+               return NL_SKIP;
 
-               struct ndmsg *ndm = NLMSG_DATA(nhm);
-               if (ndm->ndm_ifindex != iface->ifindex ||
-                               (ndm->ndm_state & NUD_FAILED))
-                       continue;
+       addrs = realloc(addrs, sizeof(*addrs)*(ctxt->ret + 1));
+       if (!addrs)
+               return NL_SKIP;
 
-               struct rtattr *rta = (struct rtattr*)&ndm[1];
-               size_t alen = NLMSG_PAYLOAD(nhm, sizeof(*ndm));
+       memset(&addrs[ctxt->ret], 0, sizeof(addrs[ctxt->ret]));
+       addrs[ctxt->ret].prefix = ifa->ifa_prefixlen;
 
-               while (RTA_OK(rta, alen)) {
-                       if (rta->rta_type == NDA_DST) {
-                               // TODO
-                               cb_neigh(NULL, iface, data);
-                               break;
-                       } else {
-                               rta = RTA_NEXT(rta, alen);
-                       }
-               }
+       nla_memcpy(&addrs[ctxt->ret].addr, nla[IFA_ADDRESS],
+                       sizeof(addrs[ctxt->ret].addr));
+
+       if (nla[IFA_CACHEINFO]) {
+               struct ifa_cacheinfo *ifc = nla_data(nla[IFA_CACHEINFO]);
 
+               addrs[ctxt->ret].preferred = ifc->ifa_prefered;
+               addrs[ctxt->ret].valid = ifc->ifa_valid;
        }
 
-       return 0;
+       if (ifa->ifa_flags & IFA_F_DEPRECATED)
+               addrs[ctxt->ret].preferred = 0;
+
+       ctxt->ret++;
+       *(ctxt->addrs) = addrs;
+
+       return NL_OK;
+}
+
+static int cb_finish_handler(_unused struct nl_msg *msg, void *arg)
+{
+       struct addr_info *ctxt = (struct addr_info *)arg;
+
+       ctxt->pending = 0;
+
+       return NL_STOP;
 }
 
+static int cb_error_handler(_unused struct sockaddr_nl *nla, struct nlmsgerr *err,
+               void *arg)
+{
+       struct addr_info *ctxt = (struct addr_info *)arg;
+
+       ctxt->pending = 0;
+       ctxt->ret = err->error;
+
+       return NL_STOP;
+}
 
 // Detect an IPV6-address currently assigned to the given interface
-ssize_t odhcpd_get_interface_addresses(int ifindex,
-               struct odhcpd_ipaddr *addrs, size_t cnt)
+ssize_t odhcpd_get_interface_addresses(int ifindex, struct odhcpd_ipaddr **addrs)
 {
-       struct {
-               struct nlmsghdr nhm;
-               struct ifaddrmsg ifa;
-       } req = {{sizeof(req), RTM_GETADDR, NLM_F_REQUEST | NLM_F_DUMP,
-                       ++rtnl_seq, 0}, {AF_INET6, 0, 0, 0, ifindex}};
-       if (send(rtnl_socket, &req, sizeof(req), 0) < (ssize_t)sizeof(req))
-               return 0;
+       struct nl_msg *msg;
+       struct ifaddrmsg ifa = {
+               .ifa_family = AF_INET6,
+               .ifa_prefixlen = 0,
+               .ifa_flags = 0,
+               .ifa_scope = 0,
+               .ifa_index = ifindex, };
+       struct nl_cb *cb = nl_cb_alloc(NL_CB_DEFAULT);
+       struct addr_info ctxt = {
+               .ifindex = ifindex,
+               .addrs = addrs,
+               .ret = 0,
+               .pending = 1,
+       };
 
-       uint8_t buf[8192];
-       ssize_t len = 0, ret = 0;
-
-       for (struct nlmsghdr *nhm = NULL; ; nhm = NLMSG_NEXT(nhm, len)) {
-               while (len < 0 || !NLMSG_OK(nhm, (size_t)len)) {
-                       len = recv(rtnl_socket, buf, sizeof(buf), 0);
-                       nhm = (struct nlmsghdr*)buf;
-                       if (len < 0 || !NLMSG_OK(nhm, (size_t)len)) {
-                               if (errno == EINTR)
-                                       continue;
-                               else
-                                       return ret;
-                       }
-               }
+       if (!cb) {
+               ctxt.ret = -1;
+               goto out;
+       }
 
-               if (nhm->nlmsg_type != RTM_NEWADDR)
-                       break;
+       msg = nlmsg_alloc_simple(RTM_GETADDR, NLM_F_REQUEST | NLM_F_DUMP);
+
+       if (!msg) {
+               ctxt.ret = - 1;
+               goto out;
+       }
+
+       nlmsg_append(msg, &ifa, sizeof(ifa), 0);
+
+       nl_cb_set(cb, NL_CB_VALID, NL_CB_CUSTOM, cb_valid_handler, &ctxt);
+       nl_cb_set(cb, NL_CB_FINISH, NL_CB_CUSTOM, cb_finish_handler, &ctxt);
+       nl_cb_err(cb, NL_CB_CUSTOM, cb_error_handler, &ctxt);
+
+       nl_send_auto_complete(rtnl_socket, msg);
+       while (ctxt.pending > 0)
+               nl_recvmsgs(rtnl_socket, cb);
+
+       nlmsg_free(msg);
+out:
+       nl_cb_put(cb);
 
-               // Skip address but keep clearing socket buffer
-               if (ret >= (ssize_t)cnt)
+       return ctxt.ret;
+}
+
+static int odhcpd_get_linklocal_interface_address(int ifindex, struct in6_addr *lladdr)
+{
+       int status = -1;
+       struct sockaddr_in6 addr = {AF_INET6, 0, 0, ALL_IPV6_ROUTERS, ifindex};
+       socklen_t alen = sizeof(addr);
+       int sock = socket(AF_INET6, SOCK_RAW, IPPROTO_ICMPV6);
+
+       if (!connect(sock, (struct sockaddr*)&addr, sizeof(addr)) &&
+                       !getsockname(sock, (struct sockaddr*)&addr, &alen)) {
+               *lladdr = addr.sin6_addr;
+               status = 0;
+       }
+
+       close(sock);
+
+       return status;
+}
+
+/*
+ * DNS address selection criteria order :
+ * - use IPv6 address with valid lifetime if none is yet selected
+ * - use IPv6 address with a preferred lifetime if the already selected IPv6 address is deprecated
+ * - use an IPv6 ULA address if the already selected IPv6 address is not an ULA address
+ * - use the IPv6 address with the longest preferred lifetime
+ */
+int odhcpd_get_interface_dns_addr(const struct interface *iface, struct in6_addr *addr)
+{
+       time_t now = odhcpd_time();
+       ssize_t m = -1;
+
+       for (size_t i = 0; i < iface->ia_addr_len; ++i) {
+               if (iface->ia_addr[i].valid <= (uint32_t)now)
+                       continue;
+
+               if (m < 0) {
+                       m = i;
                        continue;
+               }
 
-               struct ifaddrmsg *ifa = NLMSG_DATA(nhm);
-               if (ifa->ifa_scope != RT_SCOPE_UNIVERSE ||
-                               (ifindex && ifa->ifa_index != (unsigned)ifindex))
+               if (iface->ia_addr[m].preferred >= (uint32_t)now &&
+                               iface->ia_addr[i].preferred < (uint32_t)now)
                        continue;
 
-               struct rtattr *rta = (struct rtattr*)&ifa[1];
-               size_t alen = NLMSG_PAYLOAD(nhm, sizeof(*ifa));
-               memset(&addrs[ret], 0, sizeof(addrs[ret]));
-               addrs[ret].prefix = ifa->ifa_prefixlen;
-
-               while (RTA_OK(rta, alen)) {
-                       if (rta->rta_type == IFA_ADDRESS) {
-                               memcpy(&addrs[ret].addr, RTA_DATA(rta),
-                                               sizeof(struct in6_addr));
-                       } else if (rta->rta_type == IFA_CACHEINFO) {
-                               struct ifa_cacheinfo *ifc = RTA_DATA(rta);
-                               addrs[ret].preferred = ifc->ifa_prefered;
-                               addrs[ret].valid = ifc->ifa_valid;
+               if (IN6_IS_ADDR_ULA(&iface->ia_addr[i].addr)) {
+                       if (!IN6_IS_ADDR_ULA(&iface->ia_addr[m].addr)) {
+                               m = i;
+                               continue;
                        }
+               } else if (IN6_IS_ADDR_ULA(&iface->ia_addr[m].addr))
+                       continue;
 
-                       rta = RTA_NEXT(rta, alen);
-               }
-
-               if (ifa->ifa_flags & IFA_F_DEPRECATED)
-                       addrs[ret].preferred = 0;
+               if (iface->ia_addr[i].preferred > iface->ia_addr[m].preferred)
+                       m = i;
+       }
 
-               ++ret;
+       if (m >= 0) {
+               *addr = iface->ia_addr[m].addr;
+               return 0;
        }
 
-       return ret;
+       return odhcpd_get_linklocal_interface_address(iface->ifindex, addr);
 }
 
-int odhcpd_get_preferred_interface_address(int ifindex, struct in6_addr *addr)
+int odhcpd_setup_route(const struct in6_addr *addr, const int prefixlen,
+               const struct interface *iface, const struct in6_addr *gw,
+               const uint32_t metric, const bool add)
 {
-       struct odhcpd_ipaddr ipaddrs[8];
-       ssize_t ip_cnt = odhcpd_get_interface_addresses(ifindex, ipaddrs, ARRAY_SIZE(ipaddrs));
-       uint32_t preferred = 0;
+       struct nl_msg *msg;
+       struct rtmsg rtm = {
+               .rtm_family = AF_INET6,
+               .rtm_dst_len = prefixlen,
+               .rtm_src_len = 0,
+               .rtm_table = RT_TABLE_MAIN,
+               .rtm_protocol = (add ? RTPROT_STATIC : RTPROT_UNSPEC),
+               .rtm_scope = (add ? (gw ? RT_SCOPE_UNIVERSE : RT_SCOPE_LINK) : RT_SCOPE_NOWHERE),
+               .rtm_type = (add ? RTN_UNICAST : RTN_UNSPEC),
+       };
        int ret = 0;
 
-       for (ssize_t i = 0; i < ip_cnt; i++) {
-               struct odhcpd_ipaddr *ipaddr = &ipaddrs[i];
+       msg = nlmsg_alloc_simple(add ? RTM_NEWROUTE : RTM_DELROUTE,
+                                       add ? NLM_F_CREATE | NLM_F_REPLACE : 0);
+       if (!msg)
+               return -1;
 
-               if (ipaddr->preferred > preferred || !preferred) {
-                       preferred = ipaddr->preferred;
-                       *addr = ipaddr->addr;
-                       ret = 1;
-               }
-       }
+       nlmsg_append(msg, &rtm, sizeof(rtm), 0);
 
-       return ret;
+       nla_put(msg, RTA_DST, sizeof(*addr), addr);
+       nla_put_u32(msg, RTA_OIF, iface->ifindex);
+       nla_put_u32(msg, RTA_PRIORITY, metric);
+
+       if (gw)
+               nla_put(msg, RTA_GATEWAY, sizeof(*gw), gw);
+
+       ret = nl_send_auto_complete(rtnl_socket, msg);
+       nlmsg_free(msg);
+
+       if (ret < 0)
+               return ret;
+
+       return nl_wait_for_ack(rtnl_socket);
+}
+
+int odhcpd_setup_proxy_neigh(const struct in6_addr *addr,
+               const struct interface *iface, const bool add)
+{
+       struct nl_msg *msg;
+       struct ndmsg ndm = {
+               .ndm_family = AF_INET6,
+               .ndm_flags = NTF_PROXY,
+               .ndm_ifindex = iface->ifindex,
+       };
+       int ret = 0, flags = NLM_F_REQUEST;
+
+       if (add)
+               flags |= NLM_F_REPLACE | NLM_F_CREATE;
+
+       msg = nlmsg_alloc_simple(add ? RTM_NEWNEIGH : RTM_DELNEIGH, flags);
+       if (!msg)
+               return -1;
+
+       nlmsg_append(msg, &ndm, sizeof(ndm), 0);
+
+       nla_put(msg, NDA_DST, sizeof(*addr), addr);
+
+       ret = nl_send_auto_complete(rtnl_socket, msg);
+       nlmsg_free(msg);
+
+       if (ret < 0)
+               return ret;
+
+       return nl_wait_for_ack(rtnl_socket);
 }
 
 struct interface* odhcpd_get_interface_by_index(int ifindex)
@@ -381,6 +519,20 @@ static void odhcpd_receive_packets(struct uloop_fd *u, _unused unsigned int even
                struct sockaddr_nl nl;
        } addr;
 
+       if (u->error) {
+               int ret = -1;
+               socklen_t ret_len = sizeof(ret);
+               getsockopt(u->fd, SOL_SOCKET, SO_ERROR, &ret, &ret_len);
+               u->error = false;
+               if (e->handle_error)
+                       e->handle_error(e, ret);
+       }
+
+       if (e->recv_msgs) {
+               e->recv_msgs(e);
+               return;
+       }
+
        while (true) {
                struct iovec iov = {data_buf, sizeof(data_buf)};
                struct msghdr msg = {
@@ -448,7 +600,6 @@ static void odhcpd_receive_packets(struct uloop_fd *u, _unused unsigned int even
                else if (addr.in.sin_family == AF_INET)
                        inet_ntop(AF_INET, &addr.in.sin_addr, ipbuf, sizeof(ipbuf));
 
-               syslog(LOG_DEBUG, "--");
                syslog(LOG_DEBUG, "Received %li Bytes from %s%%%s", (long)len,
                                ipbuf, (iface) ? iface->ifname : "netlink");
 
@@ -460,7 +611,14 @@ static void odhcpd_receive_packets(struct uloop_fd *u, _unused unsigned int even
 int odhcpd_register(struct odhcpd_event *event)
 {
        event->uloop.cb = odhcpd_receive_packets;
-       return uloop_fd_add(&event->uloop, ULOOP_READ);
+       return uloop_fd_add(&event->uloop, ULOOP_READ |
+                       ((event->handle_error) ? ULOOP_ERROR_CB : 0));
+}
+
+int odhcpd_deregister(struct odhcpd_event *event)
+{
+       event->uloop.cb = NULL;
+       return uloop_fd_delete(&event->uloop);
 }
 
 void odhcpd_process(struct odhcpd_event *event)